Infinitely varlable switch



Sept. 1, 1942. P. H. POTTER INFINITELY VARIABLE SWITCH Filed Jan. 2,1940 Patented Sept. 1,. 1942 UNITED STATE S PATENT OFFICE 2,294,573INFINITELY VARIABLE SWITCH Paul H. Potter, Oak Park, Ill.

Application January 2, 1940, Serial No. 812,071

12 Claims.

My invention relates to electric current con having reference moreparticularly to a multiple circuit controller wherein a singleinterrupter affords difierential variation of current supply througheach circuit.

The principal objects of my invention are to provide an improvedmultiple circuit controller of the above mentioned type; to minimize thenumber of operating parts; to insure timing of the periods of currentflow in each circuit so that the current fiow periods in the severalcircuits occur consecutively; to simplify the construction of thecontroller, and permit embodiment thereof in compact form, these andother objects being accomplished as pointed out hereinafter and as shownin the accompanying drawing, in

which:

Fig. l is a top plan view of a multiple circuit controller constructedin accordance with my invention, but without cover or control knobs;

Fig. 2 is a sectional view of the controller taken on the line 2-2 ofFig. 1; and

Fig. 3 is an enlarged fragmentary sectional view on the line 3-3 of Fig.2.

Referring to the drawing in which I have, for illustrative purposes,shown the controller in a form suitable for use in electric ranges toindividually control four separate heating units or resistancesrepresented at A, B, C and D respectively, the reference numeral 5indicates the controller case which is preferably made of insulatingmaterial and of shallow square form with a bottom wall 6, surroundingside walls I and corner reinforcings 8. These corner reinforcings lterminate slightly below the top of the case to accommodate thereon theends of the four arms 8 of a spider l which said arm ends may be securedto the corner reinforcings 8 by screws II or in any other convenientmanner. The case may have a cover (not shown), attached in anyconventional way or the cover may be omitted, as for example when usedin an electric range which may be made with a pan-e1 behind which thecontroller is mounted with the heating unit controls projectingtherethrough.

A shaft I2 is located centrally in the case 5 with one end projectingthrough a bearing lit in the bottom wall 6 of the case and the latterend of the shaft is connected by a suitable coupling with the shaft of asmall motor M which is mounted on a bracket on the bottom wall 8 of thecase and operates the shaft 12 at a constant rate of speed. An eccentriccam i8 is fixed on the shaft 12 within the case and serves as a commonactuator by which all four circuits to the heating units A, B, C and Dare intermittently opened and closed, each for individually variableintervals of time according to the desired amount of heat.

A separate circuit controlling mechanism is provided for each heatingunit, each of which mechanisms includes a switch for the motor I4 and acircuit breaker operated by the eccentric cam i8 and each mechanism alsoincludes a manually adjustable cam by which a contact which cooperateswith the circuit breaker is adjustable to vary the length of time ofengagement of the circuit breaker therewith.

These four separate circuit controlling mechanisms are alike and thecor-responding parts thereof are similarly numbered in the drawing butdistinguished from one another by the suffix a, b, c, or d according tothe respective heating unit A, B, C or D to which they pertain. Only oneof these mechanisms will be described therefore and it will beunderstood that each of the others of the four separate circuitcontrolling mechanisms is the same.

Referring to the controlling mechanism for the circuit through whichcurrent is supplied to the heating unit A, the circuit breaker thereofcomprises a spring arm II which is fixed at one end to a metal bracketl8 which in turn is secured to the bottom wall 6 of the case 5 so thatthe outer end of the spring arm bears at a tension against theperipheral face of the cam l6. Thus the outer end of this spring arm I1is caused to swing outwardly in each revolution of the shaft I! adeflnlte'distance corresponding to the eccentricity of the cam i6.

The outer end of said spring arm II has an outturned portion i! with adepending extremity 20" to the inner face of which is secured a contactif which cooperates with another contact 22 on one end of a spring arm23' which has the other end fixed to a metal bracket 24- which in turnis secured to the bottom wall 6 of the case 5 so that said spring arm 28bears at a tension against the periphery of a cam 25*. a

This cam 25 is fixed on a stem 26" which is joumaled at one end in abearing 21" of the bottom wall 6 and the other end of said stem isjoumaled in and projects through one of the spider arms 9 and has a knob28' on the outer end. The stem 26 is manually operable by the knob 28"to make almost an entire revolution,

and the cam 28 is formed so that at one limit of its rotary adjustmentwith the stem 28 the spring arm 23' bears against the Periphery of thecam 25! at the point 2!- where the cam radius is such that the springarm 22 is in such position that the eccentric cam it does not impartsuiilcient swinging movement to the spring arm II to move its contact 2|away from the contact 22. Thus in this position of the cam 25' thecontacts 2| and 22' remain constantly engaged.

From the point 29" the radius of th cam 25 is gradually increasedtherearound to the point 2iat which point the radius is such as to holdthe spring arm 23' in a position in which its contact 22' is engaged bythe contact 2|! only when the spring arm I1- is in the fully retractedposition against the portion of the peripheral face of the cam i6 leastdistant from the axis of the shaft l2 and thus in each revolution of theshaft l2 and cam II the contact 2| will have only momentaryengagementwith the contact 22-. As

the cam 25' is adjusted so that the spring arm 22' bears against the camsurface between the points 30' and 29 the duration of engagement of thecontacts 2! and 22' is gradually varied from the momentary engagement atthe point 30' to continuous engagement at the point 29.

Just beyond the point N'- and between that point and the point 29, thecam 28 has a projection-Ii which engages the spring arm 23' in the finalcounter-clockwise movement of the cam 25' (as it is viewed in Fig. 1)and this projection 2| is such that when engaged with the spring arm 23*in such final position the spring arm 23" is held in a position in whichthe contact 22 thereoi'cannot be engaged by the contact 2| oi the springarm l1.

Current is supplied for energizing the heating unit or resistance A froma pair of feed wires 32 and 33, the former of which is connected as at32- with the metal bracket ll of the spring am I'l while the other feedwire 33 is connected as at 33' to a metal bracket 34 which, throughinstrumentalities hereinafter described is connectible with one end ofthe resistance of the heating unit A while the other end of saidresistance is connected as at 41' with the metal bracket 24' of thespring arm 22'. Thus when the metal bracket 34 is connected with theresistance A and the contacts 2| and 22 are engaged, current is suppliedfrom the feed wires 32 and 33 to the resistance A, the circuit from thefeed wires 32 and 23 to the resistance A being however, interruptible byseparation of the contacts 2 l and 22".

These contacts 2i and 22 are separated when the cam 25 is turned to theposition in which thi particular cam is shown wherein the proj ction 3ithereof is engaged with the spring arm 23' and this position willhereinafter be re-- ferred to as the oil" position since no current issupplied to the heating unit'A in this position of the cam.

From this "off" position the cam 25 canonly be moved in a clockwisedirection and it ma be adjusted therefrom in suchdirection to anydesired position up to the final limit of such clockwise movement (seecam 25) at which place the spring arm 23 is opposite the point 29' and pthe contact 22 positioned so that the contact esse ces plied constantlyto the heating unit A which is then operating at full heat.

When the cam 25' is adjusted so that the spring arm 23" bearsthereagainst at the point 3 (see cam 25"), which will hereinafter bereferred to as the "low position, the contact an engages the contact 22'only momentarily in each revolution of the cam and as current then issupplied to the heating unit only at intervals corresponding to the raterotation 02 the shaft is and only momentarily at such intervals, only asmall amount of current is supplied and the heating unit A will thenoperate at its lowest heat.

When the cam 25 is adjusted so that the spring arm 23 bears thereagainstat some point between the points 29' and 20, (see cam 28) the durationof engagement of the contacts 2| and 22', and the amount ofcurrent-supplied to the heating unit A will depend upon the radius ofthe cam at that particular 7 point of engagement, the form of the cam 29being such that any duration of engagement of the contacts 2| and 22'may be obtained from the momentary engagement thereof in the "low"position to the constant engagement thereof in the "high" position andaccordingly by adjustment of the cam 25" (by operating the'knob 28) theheating effect of the heating unit A can be gradually and infinitelyvaried.

It is desirable that the motor I should operate only when one or more ofthe heating units A, B, C or D are energized and accordingly each of thecontrolling mechanisms of said units has a switch operatively associatedtherewith through which current is supplied to the motor H,

, Referring again to the control mechanism of the heatingvunit A, inconnection with which there is shown a motor switch like that employedin connection with the other three control mechanisms, the referencenumeral 35 indicates a 21 cannot be disengaged therefrom, and in thisposition of the cam 25, which is hereinafter referred to as the "high"position, current is supcircular cam disk which is fixed on the shaftabovethe cam 25' and 26' a spring arm which is secured to a metalbracket 31* which is mounted on the bottom wall 6 of the case 5 so as tobear at a tension against the periphery of the disk 25. This spring arm36 is formed with a bulge 38' which in the oil position of the cam 25and its knob 28' engages a corresponding recess 29' in the periphery ofthe cam disk 25' so that the spring arm 36* occupies a retractedposition in the of! position of the knob 28 and is projected outwardlytherefrom immediately upon movement of the knob 28" from the off"position and is held in such outwardly projected position by thecircular periphery of the cam disk 35" in all positions of the knob 28*except in the "oiP position-thereof.

A contact plate Iris attached to the outer end of the spring arm 36' ina position to bridge across the contacts ll and 42 when the spring arm36 is in the outwardly projected position, the contact ll being on thebracket 34 hereinbefore referred to and the contact 42 on a separatebracket 43'- mounted on the bottom wall 6 of the case 5.

The bracket 34 is connected with the feed wire 33 and the bracket 43 hasa conductor Il leading therefrom to the motor ll which is also connectedto the other feed wire 32 by the conductor 45' so that when the contact40" is closed against the contacts Hand 42 the circuit is es-' retractedinto the recess 39'. of the cam disk and the contact plate 40'disengaged from the contacts Ii and 42.

To prevent energizing oi the heating unit A except when the motor I4 isoperating, the conductor 83 which leads to one end of the resistance ofthe heating unit A is connected therewith through the contacts ll, 42and the bridging contact 40, the bracket 81 having a conductor 48leading therefrom to the heating unit A and the bracket ll beingconnected, as hereinbeiore described, to the conductor 3!.

Thus the switch 40', ll, 41 which serves to control the operation of themotor It serves also to control the energizing of the unit A and themotor ll accordingly must necessarily operate whenever the unit A isenergized.

All of the brackets 43', 43", 43 and 43 are connected with the motor andlikewise all of the brackets 34*, 34M!" and 34 are connected with theconductor 33 so that the motor I4 is necessarily operated when any ofthe knobs 28 28 28 and 28 are turned from the 011" position and moreoverall of the brackets l8, l8", l8 and i8 areconnected with the conductor32 so that each unit A, B, C and D is independently operable althoughthe circuit interrupter of each unit is operated from the same actuator,namely the cam l6. Moreover it will be noted that the four interruptersl1, l1, I1 and i! are arranged at uniformly spaced intervals around thecam l6 so that the interrupting operations thereof occur consecutively,thereby not only minimizing the load on the motor H, but alsodistributing the energizing periods of interrupted operation of theunits A, B, C and D at equal intervals in each cycle of rotation of thecam 16 and contributing to uniformity of load on the power lines.

While I have shown and described my invention in a preferred form, I amaware that various changes and modifications may be made therein withoutdeparting from the principles of my invention, the scope of which is tobe determined by the appended claims.

I claim as my invention:

1. In a device for independently controlling a plurality of electricalcircuits, the combination of a mating pair of cooperable contacts foreach circuit by the engagement and separation of which contacts thecurrent supply in the respective circuit is controlled, a commonactuator op erable successively on a contact of each pair to causeintermittent engagement and disengagement thereof with its matingcontact in cycles varying infinitely from constantly engaged toconstantly disengaged, at least one contact of each pair beingindependently adjustable, and means for adjusting said adjustablecontact of each pair to infinitely vary the duration of engagementthereof with its mating contact, to maintain the said contactsconstantly engaged or constantly disengaged independently of said commonactuator.

2. In a device for independently controlling the supply of current to aplurality of electrically operable units, the combination of a pluralityof pairs of mating contacts each pair of which controls the supply ofcurrent to a difierent one of said units, a common interrupter for saidcontacts comprising a cam operable successively on a contact of eachpair to intermittently make and break the contact thereof, means forindividually varying the duration of intermittent contact of each pairof contacts for periods of time ranging from constant engagement of thecontacts to constant disengagement thereof and means operable toselectively interrupt the current supply to each pair of contactsirrespective of the operative position of the actuating means.

3. In a device for independently controlling the supply of current to aplurality of electrically operable units, the combination of acontinuously operated cam, a separate pair of contacts for each unit,each pair of contacts having a member operable by the cam to causeintermittent engagement and disengagement oi the respective pair ofcontacts and said members being uniformly spaced about the cam, meansfor individually varying the duration of intermittent engagement ofthe'contacts of each pair for periods of time ranging infinitely fromconstant engagement to constant disengagement, each unit having adifferent pair of said contacts associated therewith to control thesupply of current thereto and means operable to selectively interruptthe current supply to each pair oi contacts irrespective of theoperative position of the actuating means.

4. In a device for independently controlling a plurality of electricalcircuits, the combination of a separate cam means and a separate pair ofcontacts for each circuit, a single cam having the pair of contactsarranged at spaced intervals therearound, said single cam beingcooperable consecutively with each pair of contacts to vary the amountof current supplied to the respective unit and each said cam means beingmanually adjustable to individually vary the duration or contactseparation of the respective pair of contacts for varying the amount ofcurrent supplied to the respective circuit and a motor by which thecommon actuator is operated, said motor having a separate switchoperatively associated with each cam means for controlling the operationof the motor.

5. In a device for independently controlling a plurality of electricalcircuits, the combination of a separate current regulator for eachcircuit, and a common actuator for the current regulators having thecurrent regulators uniformly arranged therearound and successivelyoperable thereby, said common actuator being adapted to individuallyactuate said current regulators for periods of time varying infinitelyfrom constant operation of the said regulators to constant inoperationthereof.

6. In a device for independently regulating a plurality of electricalcircuits, a plurality of pairs of contacts each controlling anelectrical circuit, at least one contact of each of said pairs beingmovable into and out of engagement with its mate, a common operatingmeans for intermittently actuating said movable contacts into and out ofengagement with their respective mates, and means associated with eachof said pairs for infinitely varying the periods of intermittentengagement of the contacts thereof effected by said common operatingmeans and for maintaining the said contacts constantly engaged orconstantly disengaged independently of said common operating means.

"7. In a device for independently regulating a plurality of electricalcircuits, a plurality of pairs of contacts each controlling anelectrical circuit, at least one contact of each of said pairs beingmovable into and out of engagement with its mate, a common operatingmeans for intermittently and successively actuating said movablecontacts into and out of engagement with their respective mates, andmeans associated with each of said pairs for individually and infinitelyvarying the periods of intermittent eng gement of a combination of twooppositely biased switch alethe contacts'thereot eflected by said commonoperating means and for maintaining the said contacts constantly engagedor constantly disengaged independently of said common operating means.

,8. In a device for independently regulating a plurality of electricalcircuits, a plurality of. pairs of contacts each controlling anelectrical circuit,

at least one contact each of said pairs being movable into and out I ofengagement with its mate, a common operating means in the tom of arotating power driven cam for intermittently actuating said movablecontacts into and out of engagement with their respective mates, meansassociated with each of said pairs for infinitely varying the periods-ofintermittent engagement of the contacts thereof effected by said commonoperating means and for maintaining the said contacts constantly engagedor constantly disengaged independently 01 said common operating means,and means cooperatively associated with said latter means fordisestablish'ing a source 01' power for said common operating means whensaid contacts are in constantly disengaged relation.

9. In a device for periodically supplying current for selectivelyvariable lengths of time, the combination of two oppositely biasedswitch elements each normally tending to enga e the other, a constantlyoperable, actuator by which one of said elements is periodically movablein a direction away from the other element, manually adjustable meansagainst which one oi! said ele- 1 ments is biased and by which theduration of periodic current supply is selectively variable, and meansassociated with said adjustable means and operable in'one position ofthe latter for disestablishing a source of power for said actuator.

10.- In a device for periodically supplying current for selectivelyvariable lengths 0! time, the

ments each normally tending to engage the other, a constantly operableactuator by which one or said elements is periodically movable in adirection away from the other element, and manually operable means bywhich the latter element is adiustable away irom the other element tovary the duration of contact of the elements with one another, or tomaintain said. elements constantly disengaged irrespective of theoperative position oi. the said actuator.

11. In a .d8vice for periodically supplying current for selectivelyvariable lengths of time, the

combination of two cooperatively associated oppositely biased switchelements, a constantly operable actuator by which one of said elementsis periodically movable toward and away from the other element, andmanually operable means by which thelatter element is adjustable withrespect to the first element to vary the duration of contact of theelements with one another, or to maintain said elements constantlydisengaged irrespective of the operative position of the said actuator.

12. In a device for periodically supplying currentfor selectivelyvariable lengths of time, the combination of two switch elements atleast one of which is biased towardand normally tends to engage theother, a constantly operable actuator by which said biased element isperiodically movable in a direction away from the other element,-

and manually operable means by which the latter element is adjustableaway from the biased element to vary the duration of contact of theelements with one another, or to maintain said elements constantlydisengaged irrespective oi th operative position of the said actuator.

PAUL H. POTTER.

